1. Field
The present disclosure relates to sensors and more particularly to thermal/overheat sensing in aircraft, land based applications, and in vehicles.
2. Description of Related Art
Thermal sensing in aircraft components (e.g., a hot air duct from an engine for environmental control) can utilize heat-sensing elements disposed therein for monitoring the components for overheating. Current duct leak overheat detection systems (DLODS) use a nickel-containing inner core electrode and an Inconel® 625 outer sheath electrode separated by a granular, porous ceramic or glass layer. This granular, porous ceramic layer is filled with a salt mixture and acts as an electrical barrier between electrodes when exposed below a threshold temperature. The salt mixture melts at a threshold temperature and causes an electrical connection between the inner electrode and the outer electrode such that the salt mixture is a heat-sensing element.
However, in traditional sensors, the ceramic layer is broken inside the sheath layer randomly and the salt mixture is distributed randomly throughout the ceramic layer, which can potentially cause inconsistent performance. Also, the random breaking of the ceramic layer and bending of the sensor can lead to portions where the outer electrode is closer to the inner electrode which changes the axial capacitance causing difficulty in locating failures in the sensor.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved thermal sensors. The present disclosure provides a solution for this need.